1. Field of the Invention
The present invention relates to a camera using a recording medium in which an object image obtained through a photographing optical system is electronically developed, and more particularly, to a device for assessing the quality of the recording medium.
2. Description of the Related Art
Conventionally, as disclosed in Japanese Unexamined Patent Publication No. 5-2280 and U.S. Pat. No. 5,424,156, there is known a photographic material which is directly electronically developed so that the developed visible image can be immediately obtained. In this specification, such a recording medium is referred to as an electro-developing recording medium, and an electronic still camera using the electro-developing recording medium is referred to as an electro-developing type camera.
Japanese Unexamined Patent Publication Nos. 5-165005, 6-130347 and 7-13132 disclose an electro-developing recording medium which comprises a liquid crystal display having a memory-type liquid crystal so that an image indicated on the liquid crystal display is kept even if the electric field applied to the liquid crystal display is removed. '347 and '132 disclose an electro-developing recording medium in which the electrostatic information recording medium and the electric charge storage medium are combined to form one body. Namely, in these electro-developing recording mediums, even if an electric voltage applied thereto is removed, the image formed on the electro-developing recording medium is kept.
For recording a clear image on the electro-developing recording medium, the applied electric voltage and the voltage application period on the recording medium are important components (see Japanese Unexamined Patent Publication No. 6-313872). These components depend upon the characteristics, i.e., the resistances and the electrostatic capacities of an electric charge storage medium and an electrostatic information recording medium which are provided in the electro-developing recording medium. Especially, the resistance of the electrostatic information recording medium is greatly affected by the environment such as temperature around the electro-developing recording medium. Namely, by detecting the resistance before the recording operation, the applied electric voltage and the voltage application period on the electro-developing recording medium can be properly controlled.
If the resistance of the electrostatic information recording medium is greatly lowered due to moisture absorption thereof, for example, the difference between an electric current generated in a portion in which the light receiving amount is large and that in a portion in which the light receiving amount is small would become small. Thus, a problem would occur in which a contrast between the bright portion and the dark portion is reduced and a clear image can not be recorded on the electro-developing recording medium.